Heat and mass transfer parameters in the drying of cocoyam slice

The paper investigates some heat and mass transfer parameters (HMTPs) of three varieties of cocoyam slice and their vitamin B retention level in convective drying. The varieties include Colocasia esculenta (COE) and xanthosoma sagittiffolium (white flesh – NX01, red flesh – NX02). The objective is to generate HMTPs for process model development, applied in dryer design. The oven and sun drying procedures were employed where temperatures were maintained between 50 and 70 °C (oven drying) and sun drying, the readings were observed at every one hour. The results obtained show that the mass transfer coefficient for the three varieties lies between 1.01044×10−6 and 3.44876×10−6 m/s while the heat transfer coefficient ranged from 1.17973 to 3.58284 W/m2 K. The specific energy consumption for drying was estimated at 14.15, 25.16 and 35.07 kWh/kg for NX02, NX01, and COE respectively, at drying temperature (DT) of 60 °C. However, at DT range between 50 and 70 °C the moisture extraction rate was varied from 0.047 to 0.185 kg/kWh, for NX02, 0.070–0.258 kg/kWh for NX01 and 0.099–1.42 kg/kWh for COE, with vitamin B retention level ranging from 70.13% to 100% at all DTs for the varieties.

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